1. Field of the Invention
The present invention relates to a technique of charging a battery internally attached to a radiation imaging apparatus.
2. Description of the Related Art
Conventionally, an X-ray image taken using radiations, such as X-rays, has been widely used for disease diagnosis. Furthermore, an X-ray imaging apparatus has been commercialized that applies image processing to an X-ray image taken by the X-ray imaging apparatus and generates a clearer X-ray image. When an X-ray image is taken, the X-ray imaging apparatus is typically installed on one of a mount and a bed in a fixed manner. However, to increase installation flexibility of the X-ray imaging apparatus on imaging, in some cases, the X-ray imaging apparatus is not mechanically fixed but takes an image at a free position instead. As an example to meet such requirements, for instance, Japanese Patent No. 3,494,683 discloses an X-ray imaging apparatus that adopts wireless communication to increase installation flexibility on imaging.
Adoption of wireless communication for increasing the installation flexibility of the X-ray imaging apparatus on imaging requires a battery in the X-ray imaging apparatus (hereinafter, called an internal battery). A rechargeable internal battery capable of being repeatedly used can be employed. Schemes of charging an internal battery include a dedicated charger scheme in which an internal battery is removed from an X-ray imaging apparatus, the battery is attached to a dedicated charger and the charger charges the battery, and a main body charging scheme in which an internal battery is charged in a state where the battery is attached to an X-ray imaging apparatus and a power source cable is connected to the X-ray imaging apparatus.
The dedicated charger scheme and the main body charging scheme have their own advantages. The advantage of the dedicated charger scheme is that, while the X-ray imaging apparatus is used through wireless communication, another internal battery can be charged independently and in parallel. That is, when the power of the internal battery used in the X-ray imaging apparatus is lost, the battery is replaced with another internal battery having been charged independently in parallel, thereby allowing the operation of taking an X-ray image to be immediately restarted. The advantage of the main body charging scheme is that, in the case where use of the X-ray imaging apparatus through wireless communication is not specifically required, the power source cable is connected to the X-ray imaging apparatus and the apparatus is used through wired communication, thereby allowing the operation of taking an X-ray image while charging the internal battery without consuming power accumulated in the internal battery. Thus, the dedicated charger scheme and the main body charging scheme have their own advantages. The X-ray imaging apparatus is required to have both functions of the dedicated charger scheme and the main body charging scheme.
In the X-ray imaging apparatus having the functions of both the dedicated charger scheme and the main body charging scheme, electric circuits and an X-ray sensor of which temperatures increase by power consumption are enclosed in a sealed housing because of necessity to block external light. Accordingly, in some cases, the temperature becomes as high as more than 50° C. It is known that, if the internal battery is left in a state of being at a high temperature and fully charged, deterioration of the internal battery is enhanced to reduce the life thereof. However, conventionally, in operation of the X-ray imaging apparatus, even though the internal temperature becomes high, the internal battery is sometimes left in a state of being fully charged. Accordingly, deterioration of the internal battery is enhanced. As a result, a time for taking an X-ray image is unfortunately reduced. In order to remove such troubles, the present invention which can prevent the battery from deteriorating and increase the battery life is provided.